Diastolic pressure is the vascular pressure created during the pulmonary resting phase.
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Chapter 5: Blood Pressure Show Blood pressure is the force of blood exerted against the arterial walls, and is reported in millimetres of mercury (mm Hg). Try turning your kitchen tap on just a little bit, and then full blast. Compare the varying forces of water pressure as you adjust the tap. This comparison will give you a better sense of blood pressure. The pressure against the arterial walls (the blood pressure) changes depending on whether the heart is contracting and pushing blood out into the arteries or whether the heart is in a resting phase and filling with blood. There is always force against the arterial walls, even when the heart is in a resting phase. The systolic pressure is the maximum pressure on the arteries during left ventricular contraction (systole) (OER #1). The left ventricle is a lower chamber of the heart responsible for pumping blood out to the body. The diastolic pressure is the resting pressure on the arteries between each cardiac contraction (OER #1) when the heart’s chambers are filling with blood (diastole). Stroke volume is the amount of blood ejected from the left ventricle in a single contraction. Stroke volume provides information about the functioning of the heart. Stroke volume is influenced by age and typically ranges from 5–80 mL. Newborns have a stroke volume of about 5 mL per contraction while adults have a stroke volume of about 30–70 mL per contraction; the stroke volume increases as individuals grow and their hearts become stronger and can pump more volume per contraction. Direct measurement of stroke volume involves an invasive approach in which a catheter is passed into the pulmonary artery via a large neck vein; this monitoring device is only used during critical care situations. Indirect measurement of stroke volume involves assessing the pulse pressure, which is the difference between the systolic and diastolic values and signifies the force required by the heart each time it contracts. For example, if someone’s blood pressure is 120/80 mm Hg, the pulse pressure is 40 mm Hg. A higher pulse pressure can indicate arterial stiffness, which often happens as a result of aging or cardiovascular disease. A higher pulse pressure can also be indicative of aortic valvular insufficiency where the diastolic pressure is unusually low and the systolic pressure is mildly elevated or unchanged. A lower pulse pressure can be a marker of poor heart function, where cardiac output is decreased. Test Your KnowledgePlease answer the four questions in the following question set. Chapter AttributionsPart of this content was adapted from OER #1 (as noted in brackets above):
What is diastolic pressure and how is it generated?The diastolic blood pressure is the minimum pressure experienced in the aorta when the heart is relaxing before ejecting blood into the aorta from the left ventricle (approximately 80 mmHg). Normal pulse pressure is, therefore, approximately 40 mmHg.
What is the end diastolic pressure?The volume of blood in the left ventricle at the end of ventricular filling is called the end-diastolic volume (EDV), which is about 120 mL in the adult human. The corresponding pressure, the end-diastolic pressure (EDP), is about 4–7 mmHg.
What determines the diastolic pressure?Diastolic blood pressure is mainly determined by: Total arterial peripheral resistance (major influence) Arterial elastance and compliance. Time constant of the peripheral vessels (and therefore heart rate)
Is diastolic pressure higher in pulmonary circulation?Blood pressures within the pulmonary circulation are significantly lower than those of the systemic circulation across all vessels. For example, Pulmonary arterial pressures average 15 mm Hg and fluctuate between 25 mm Hg systolic pressure and 8 mm Hg diastolic pressure.
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